1. Field of the Invention
This invention relates generally to semiconductor products manufacturing, and, more particularly, to a method and apparatus for monitoring process performance using statistical process control and advanced process control.
2. Description of the Related Art
The technology explosion in the manufacturing industry has resulted in many new and innovative manufacturing processes. Today""s manufacturing processes, particularly semiconductor manufacturing processes, call for a large number of important steps. These process steps are usually vital, and, therefore, require a number of inputs that are generally fine-tuned to maintain proper manufacturing control.
The manufacture of semiconductor devices requires a number of discrete process steps to create a packaged semiconductor device from raw semiconductor material. The various processes, from the initial growth of the semiconductor material, the slicing of the semiconductor crystal into individual wafers, the fabrication stages (etching, doping, ion implanting, or the like), to the packaging and final-testing of the completed device, are so different from one another and specialized that the processes may be performed in different manufacturing locations that contain different control schemes.
Among the important aspects in semiconductor device manufacturing are RTA control, chemical-mechanical planarization (CMP) control, and overlay control. Overlay is one of several important steps in the photolithography area of semiconductor manufacturing. Overlay control involves measuring the misalignment between two successive patterned layers on the surface of a semiconductor device. Generally, minimization of misalignment errors is important to ensure that the multiple layers of the semiconductor devices are connected and functional. As technology facilitates smaller critical dimensions for semiconductor devices, the need for reduced misalignment errors increases dramatically.
Generally, photolithography engineers currently analyze the overlay errors a few times a month. The results from the analysis of the overlay errors are used to make updates to exposure tool settings manually. Generally, a manufacturing model is employed to control the manufacturing processes. Some of the problems associated with the current methods include the fact that the exposure tool settings are only updated a few times a month. Furthermore, currently the exposure tool updates are performed manually. Many times, errors in semiconductor manufacturing are not organized and reported to quality control personnel. Often, the manufacturing models themselves incur bias errors that could compromise manufacturing quality.
Generally, a set of processing steps is performed on a lot of wafers on a semiconductor manufacturing tool called an exposure tool or a stepper. The manufacturing tool communicates with a manufacturing framework or a network of processing modules. The manufacturing tool is generally connected to an equipment interface. The equipment interface is connected to a machine interface to which the stepper is connected, thereby facilitating communications between the stepper and the manufacturing framework. The machine interface can generally be part of an advanced process control (APC) system. The APC system initiates a control script based upon a manufacturing model, which can be a software program that automatically retrieves the data needed to execute a manufacturing process. Often, semiconductor devices are staged through multiple manufacturing tools for multiple processes, generating data relating to the quality of the processed semiconductor devices. Many times, errors in semiconductor manufacturing are not organized and reported to quality control personnel, which can result in reduced efficiency in manufacturing processes. Errors in the manufacturing model that is used to perform the manufacturing process, such as bias errors, often compromise the quality of manufactured products.
Often, in semiconductor manufacturing, statistical process control (SPC) is used to enhance the production control of manufacturing of semiconductor wafers. SPC is generally used for controlling the production line from a broad-control point of view. SPC generally monitors manufacturing parameters and activates alarms when the manufacturing parameters become out of control; whereas a process controller, such as the APC, performs fault detection and fine-tunes control of manufacturing of semiconductor wafers. The industry currently lacks an efficient means of utilizing the resources of the APC in conjunction with SPC to improve production of semiconductor devices.
The present invention is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.
In one aspect of the present invention, a method is provided for interfacing a statistical process control system with a manufacturing control system. A manufacturing model is defined. A processing run of semiconductor devices is processed in a manufacturing facility as defined by the manufacturing model. An advanced process control analysis is performed on the processed semiconductor devices. A statistical process control analysis is performed on the processed semiconductor devices. The manufacturing facility is modified in response to the advanced process control analysis and the statistical process control analysis.
In another aspect of the present invention, an apparatus is provided interfacing a statistical process control system with a manufacturing control system. The apparatus of the present invention comprises: a processing controller; a processing tool coupled with the processing controller; a metrology tool interfaced with the processing tool; a communications interface coupled with the processing controller, the communications interface being capable of sending feedback signals to the processing controller; a control modification data calculation unit interfaced with the metrology tool and connected to the communications interface in a feedback manner for performing feedback adjustments; a predictor function interfaced with the processing controller; a statistical process control analysis unit interfaced with the predictor function and the processing tool; and a results versus prediction analysis unit interfaced with the statistical process control analysis unit and connected to the communications interface in a feedback manner for performing feedback adjustments.